Method of building a tire with no bead turnup

ABSTRACT

A method of building a tire having no ply turnup is described. The method includes the steps of applying an inner liner and chafer onto a tire building drum; radially expanding the center portion of the drum and applying a first column bead, applying a layer of ply followed by a second column bead, turning up the chafer and then inflating the carcass under low pressure below 150 mbars, applying the tread, applying the sidewall. A method of molding a green tire having a first and second bead area is described herein, wherein the method includes the steps of: inserting a tire clamping device inside a tire bladder and then inserting the tire clamping device and the bladder into the green tire, aligning the outer surfaces of the tire clamping device are in engagement with a respective bead area of the tire so that each tire bead area is clamped between a respective upper and lower mold ring and the tire clamping device during cure.

FIELD OF THE INVENTION

The invention relates generally to tires and more particularly to apneumatic tire.

BACKGROUND OF THE INVENTION

For high performance and ultrahigh performance tires, it is oftendesired to eliminate the ply turnup around the bead. Eliminating the plyturnup removes the stress concentration and allow construction usinglarger diameter reinforcing cords. However, it is difficult to build thetire without building the tire on a solid core. The ply cord typicallypulls out from the bead during the tire curing process, because of therapid expansion and transformation from green built dimensions to cureddimensions of the tire carcass during the cure process. The solid coreeliminates the movement of the carcass. However, building a tire on asolid core requires special equipment and often is a much slower tirebuilding process. Thus, it is desired to provide a method and apparatusfor building a tire that has no ply turnup using conventional tirebuilding equipment.

SUMMARY OF THE INVENTION

The invention provides in a first aspect of the invention a method ofmolding a green tire having a first and second bead area, the methodcomprising the steps of : inserting a tire clamping device inside a tirebladder and then inserting the tire clamping device and the bladder intothe green tire, aligning the outer surfaces of the tire clamping deviceinto engagement with a respective bead area of the tire and a respectiveupper and lower mold ring so that each bead area is clamped between therespective mold ring and the tire clamping device during cure.

Definitions

“Aspect ratio” of the tire means the ratio of its section height (SH) toits segment width (SW) multiplied by 100 percent for expression as apercentage.

“Axial” and “axially” means lines or directions that are parallel to theaxis of rotation of the tire.

“Chafer” is a narrow strip of material placed around the outside of atire bead to protect the cord plies from wearing and cutting against therim and distribute the flexing above the rim.

“Circumferential” means lines or directions extending along theperimeter of the surface of the annular tread perpendicular to the axialdirection.

“Equatorial Centerplane (CP)” means the plane perpendicular to thetire's axis of rotation and passing through the center of the tread.

“Footprint” means the contact patch or area of contact of the tire treadwith a flat surface at zero speed and under normal load and pressure.

“Groove” means an elongated void area in a tire dimensioned andconfigured in segment for receipt of an air tube therein.

“Inboard side” means the side of the tire nearest the vehicle when thetire is mounted on a wheel and the wheel is mounted on the vehicle.

“Lateral” means an axial direction.

“Lateral edges” means a line tangent to the axially outermost treadcontact patch or footprint as measured under normal load and tireinflation, the lines being parallel to the equatorial centerplane.

“Outboard side” means the side of the tire farthest away from thevehicle when the tire is mounted on a wheel and the wheel is mounted onthe vehicle.

“Radial” and “radially” means directions radially toward or away fromthe axis of rotation of the tire.

“Rib” means a circumferentially extending strip of rubber on the treadwhich is defined by at least one circumferential groove and either asecond such groove or a lateral edge, the strip being laterallyundivided by full-depth grooves.

“Sipe” means small slots molded into the tread elements of the tire thatsubdivide the tread surface and improve traction, sipes are generallynarrow in width and close in the tires footprint as opposed to groovesthat remain open in the tire's footprint.

“Tread element” or “traction element” means a rib or a block elementdefined by a shape with adjacent grooves.

“Tread Arc Width” means the arc length of the tread as measured betweenthe lateral edges of the tread.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described by way of example and with reference tothe accompanying drawings in which:

FIG. 1 is a cross-sectional view of a tire with no bead turnup;

FIG. 2 is a close-up view of the bead area of the tire of FIG. 1 anddepicts variants in wires for bead columns;

FIG. 3 is a schematic of a tire building drum shown with the innerliner, chafer, and toeguard applied;

FIG. 4 illustrates the tire building drum shown with the crown expanded;

FIG. 5 illustrates the tire building drum shown with the crown expandedand the first bead being formed;

FIG. 6 illustrates the tire building drum shown with the crown expandedand the ply layer being applied;

FIG. 7 illustrates the tire building drum shown with the crown expandedand the second bead being formed;

FIG. 8 illustrates the tire building drum shown with the crown expandedand the chafers being turned up by bladders;

FIG. 9 illustrates the green carcass being inflated with no bead lockpressure;

FIG. 10 illustrates the tread being applied to the shaped green carcass;

FIG. 11 illustrates the application of the sidewall over the tread;

FIG. 12 illustrates a perspective view of a tire clamping device in theclosed position;

FIG. 13 illustrates a top view of the tire clamping device of FIG. 12 inthe closed position;

FIG. 14 illustrates a perspective view of the tire clamping device inthe open position; and

FIG. 15 illustrates a cross-segmental schematic of a tire in the tiremold with the ply clamping device and bladder installed.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

FIG. 1 illustrates a tire 10 of the present invention that has no beadturnup. The tire 10 has a single layer or monolayer of ply 20, that hasa radially inner portion 22 that is clamped between a first column bead30 and a second column bead 40. The tire 10 may further include a tread50, and belts 60. The invention is not limited to the beads columns asshown. There could also be variants of the columns inside or outside ofthe ply. Columns could be formed by traditional strap beads in theconfiguration of 2=11. Columns could also be made by spirally windingvarious wire treatments.

The tire 10 may be formed on a conventional two stage tire building drum300 that has a crowning or radially expandable center portion 310, wherecrowning and bead locking functions are fully independent of each other.FIG. 3 illustrates that the tire 10 may be building by applying theinner liner 320, toeguard 322 and chafer 324 to the tire building drum.As shown in FIG. 4, the tire drum center portion may be radiallyexpanded. As shown in FIG. 5, the first column bead may be applied byeither applying a preassembled column bead 330 onto the tire drum, or byspirally winding a continuous wire onto the drum to form a column bead330. Those skilled in the art would understand that the apparatus (notshown) to create a forging force to friction weld the materialstogether. Also, those skilled in the art would understand that variouschemical adhesive coupons could be added to the assembly for additionalwelding in the green state. The column bead may be preassembled with anapex (not shown). Next, as shown in FIG. 6 a single layer of ply 350 isapplied onto the drum. Next, as shown in FIG. 7, the drum is rotated asa wire is wound onto the assembly to form a second column bead 360. Asecond apex is then applied adjacent the second bead 360. The first andsecond column bead function to clamp the ply.

FIG. 8 illustrates that the chafer 324 is turned up by the bladders (notshown) of the tire building drum.

FIG. 9 illustrates that the carcass is inflated using low pressure air,under 150 mBars. There is minimal bead lock force being applied; onlyenough force to seal the carcass shaping air from leaking. FIG. 10illustrates that the tread is applied to the inflated carcass and thenstitched. FIG. 11 illustrates that the sidewall is then applied, whereinthe sidewall has a radially outer portion that extends over laterallyouter end of the tread.

Next, the shaped green tire is removed from the drum. In order to curethe tire, the tire clamping device 100 as described in more detail,below, is inserted inside a curing bladder (not shown). Next, the tirecuring bladder with the tire clamping device inside is positioned in themold. A vacuum is drawn on the tire bladder which results in the tireclamping device being collapsed into the closed position. Next, thegreen carcass is slipped over the closed tire clamping device andbladder. Next, the bladder is inflated and the springs of the tireclamping device are released, so that the segments are biased in aradially outward direction. The bead area 300 of the green carcass andbladder is clamped between the outer portions 122,120 of the tireclamping device and the respective upper and lower mold rings 230,240.Next, the tire is cured when the tire clamping device is in place toensure that the ply remains positioned between the beads during cure andnot pulled out of place due to the tire shaping pressure. Thus, the tireclamping device is sized so that when in the collapsed position, itsouter diameter is less than the bead diameter, and capable ofresiliently expanding so that its outer diameter in the expandedposition is greater than the bead diameter of the green carcass to becured.

Tire Clamping Device

FIG. 12 illustrates a perspective view of a tire clamping device 100that is used to clamp the bead area of the tire in the mold to ensurethe ply of the green carcass is clamped between the tire clamping device100 and the tire mold. This allows a tire to be cured that does not havea ply turnup, and solves the problem of ply pullout during the cure whenthe tire is cured without a core.

The tire clamping device 100 includes a plurality of segments110,112,114 and 116. As shown in FIG. 13, when the segments are in thefully closed position, the tire clamping device has a round shape. Theplurality of segment when joined together in the closed position, formouter rings 120,122 that engages the tire bead and the lower radialportion of the curing bladder 130 and hold the ply in place during cure.

FIG. 14 illustrates that the segments 110,112,114, and 116 each haverespective radially oriented springs 116 a,b, 110 a,b, 112 a,b and 114a,b. The radially oriented springs bias the segments 110,112,114,116 inthe radially expanded position. Each segment also has guide rails 110 c,112 c, 114 c, 116 c. The radially oriented springs and the guide railsare located between the respective segments and an inner portion 130, inthe example shown as a center square block 130 (although not limited tothe square configuration).

FIG. 14 illustrates that the segments 110,112,114, and 116 each havetransverse or axially oriented (with respect to the tire) springs 110 d,112 d, 114 d, and 116 d that are perpendicular to the radially orientedsprings. The springs may be replaced with other mechanical mechanismsknown to those skilled in the art, to facilitate opening and closing thetire clamping device.

FIG. 15 illustrates a typical mold 200 used for curing passenger tires.The mold 200 has tread plates 210 for molding the tread of a tire, andsidewall plates 220 for forming the sidewalls of the tire. Each sidewallplates has a lower portion 222 located in the bead area of the tire. Themold further includes upper and lower mold rings 230,240 that arelocated adjacent the lower portion 222 of the sidewall plates. The themold rings work together with the tire clamping device to clamp the plyand bead area of the green tire during the cure.

Variations in the present invention are possible in light of thedescription of it provided herein. While certain representativeembodiments and details have been shown for the purpose of illustratingthe subject invention, it will be apparent to those skilled in this artthat various changes and modifications can be made therein withoutdeparting from the scope of the subject invention. It is, therefore, tobe understood that changes can be made in the particular embodimentsdescribed which will be within the full intended scope of the inventionas defined by the following appended claims.

What is claimed:
 1. A method of building a tire having no ply turnup,the method comprising the steps of: applying an inner liner and chaferonto a tire building drum; radially expanding the center portion of thedrum and applying a first column bead; applying a layer of ply followedby a second column bead; and turning up the chafer and then inflatingthe carcass under low pressure below 150 mbars, applying the tread,applying the sidewall.
 2. The method of claim 1 wherein the first columnbead is formed by winding a wire onto the tire building drum.
 3. Themethod of claim 1 wherein the second bead is formed by winding a wireonto the tire building drum.
 4. The method of claim 1 further comprisingthe steps of molding a green tire having a first and second bead area,the method comprising the steps of: inserting a tire clamping deviceinside a tire bladder and then inserting the tire clamping device andthe bladder into the green tire; and aligning the outer surfaces of thetire clamping device into engagement with a respective bead area of thetire so that each tire bead area is clamped between a respective upperand lower mold ring and the tire clamping device during cure.
 5. Amethod of molding a green tire having a first and second bead area, themethod comprising the steps of: inserting a tire clamping device insidea tire bladder and then inserting the tire clamping device and thebladder into the green tire; and aligning the outer surfaces of the tireclamping device into engagement with a respective bead area of the tireso that each tire bead area is clamped between a respective upper andlower mold ring and the tire clamping device during cure.
 6. The methodof claim 1 further comprising the step of pulling a vacuum so that thetire clamping device is positioned into the closed position.
 7. Themethod of claim 1 further including the step of inflating the bladder sothat the segments of the tire clamping device are resiliently biasedinto an open position.